It's Fleet Week here in San Francisco and that means Navy Flight Demonstration Squadron aka The Blue Angels are back in town for the celebration. This is what it takes to convert a battle-ready F/A-18 Hornet into a marvelous stunt-flying Angel.

The Blue Angels flight exhibition team was formed in 1946 by order of Admiral Chester Nimitz in order to boost morale and demonstrate the Navy's fighting prowess (and gain public favor to counteract a shrinking budget). The original team flew modified Grumman F6F-5 Hellcats and has flown a total of nine aircraft in the 65 years since. The F/A-18 Hornet is the latest to be employed by the team and has been in service since 1986 when it replaced the A-4 Skyhawk.

The Hornets in the Blue Angel Squad have been significantly modified from those that see active combat. In addition to an extra inverted fuel pump allowing for longer inverted flights without the engine becoming fuel-starved and a high-gloss, low-friction paint to reduce drag, the M61 Vulcan machine gun in the nose cone has been replaced with a tank that holds the jet's supply of smoke oil.

The colored smoke that the jets produce is made by injecting a biodegradable paraffin-based oil into the plane's exhaust nozzles, instantly vaporizing it. It not only allows spectators to follow along more easily, these smoke trails increase each pilot's visibility to the rest of the team.

The Blue Angels planes also handle differently from the combat model thanks to the installation of a small spring on the command stick that applies 40 pounds of nose-down pressure—making the plane easier to fly in formation and upside-down while increasing the stick's sensitivity. However, that also means the pilot must continually overcome that added pressure to maintain a level flight path.

In addition, because of space restrictions in the cockpit the Blue Angels pilots don't wear G-suits, whose constant inflating and deflating air bladders would interfere with controlling the plane. However, since the flights are coordinated, the pilots know when high G maneuvers are coming up and can perform the same task manually by clenching their stomach and leg muscles to prevent blood from rushing from their heads to their lower bodies, causing them to black out.

And while they aren't battle-ready per se, they can be transitioned back to battle-ready status (repainted and rearmed) within 72 hours were the need to arise.

The biggest difference between a Hornet and an Angel is not what they're equipped with but what they run on. Hornets get the traditional jet fuel but the Angels run on a 50-50 mix of plant-based bio-fuels and conventional fuel, making it the first and only full Navy squadron to fly with biofuels.

The US military is actually the single largest energy consumer in the country with oil providing 80% of that requirement but has aggressively developing alternatives—as well they should given that a $1 increase in the price of a barrel of oil translates into a $30 million energy cost increase for the Navy alone. Between 2006 and 2009, the Pentagon tripled its spending on alternative energies from $400 million to $1.2 billion.